Obviously, if it was me, I'd now move all non actual Puppy Linux distros into Other Distros since they are not Puppy.
But especially that Dog-incubator section which was just created (by me) as a holder for these what-are-really pure Tiny Core based projects - albeit with Puppy lookalike additions. However, gives you a dilemma since FatDog is only Puppy lookalike and DebianDogs not even so lookalike. Nevertheless, Dog-incubation should no longer be encouraged so are logically Other Distros section
But also, yes, deprecated - nothing being done on them for long long time now, and nothing probably likely to.
Fact is, the forum discussions can continue between members whether their non-Puppy project is featured in these discussions here or not.
Puppy may not grow or radically change, but that is up to Puppy and its woof-CE situation.
As for all these non-Puppy distros - maybe their dev teams can decide to collaborate and make a single forum of their own, if not separate to their absolutely own forums altogether? Then again, maybe not. It is difficult to see, looking at the forum first page, how they fit into the current structure aside from that little one-line exposure they each individually get - but hardly looks representative of their popularity overall.
Or maybe over time you could somehow work towards a multi-Mainpage - being one per major such distro, rather than a small section in Other distros which is itself a tiny section in Off-Topic; I don't know how easy or possible it is to arrange a phpBB forum such that each distro could have similar facilities as Puppy Linux main page, maybe with some sort of menu first page such that Puppy becomes just one of the main distro pages pointed to? Big job probably, so again, maybe not. And the non-inclusive domain name leaves a problem anyway.
So easiest is just to move Dog Incubator and otherwise stick with current status quo since no one now complaining about it anyway.